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Questions Regarding Hybrid Heating System with Honeywell Prestige 2.0

Questions Regarding Hybrid Heating System with Honeywell Prestige 2.0


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Old 02-02-13, 08:23 AM
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Questions Regarding Hybrid Heating System with Honeywell Prestige 2.0

Hi everyone,

I recently bought my house and we were told that we have an 'unconventional' heating system by both the previous owners and our home inspector when we bought the house. Our primary heat system is our Heat Pump, however, we have a gas auxiliary/emergency heat. The previous owner and the home inspector both said to use the emergency heat whenever it got below 30 degrees or so as it was more efficient than the heat pump (being that it's gas).

I recently bought a Honeywell Prestige 2.0 to replace the original 30 year old thermostat. That being said, I installed the thermostat with my father and when we got to wiring the Emergency Heat (black) wire, we weren't sure what to do with the black wire, so we decided to just cap it off until we could figure out where to put it. Now that it's rather cold here in Maryland (20 degrees or so), I'm wondering where I need to put the wire and how I could configure the thermostat to work with the different setup that we have.

According to the manual, the 'L/A terminal sends continuous output when thermostat is set to EM HEAT mode, except when setup for Economizer or TOD. See Economizer wiring section.' I do not own the Economizer, so I tried connecting the black wire to the L/A terminal and set the Thermostat to "Emergency Heat" -- the problem with this is that it doesn't seem to care about the Heat Setpoint and just runs all of the time, regardless of the temperature. I've included pictures of the old thermostat's wiring as well as the new thermostat's wiring.

Is there a way to wire this (maybe wire white and black wires together in together?) for me to be able to use the Emergency Heat/Gas backup when it's below 30 degrees, but use the Heat Pump above this? I don't mind manually switching to EM HEAT on the thermostat, but the thermostat isn't working/shutting it off.

Old:

New:



Thank you in advance!

Chris
 
  #2  
Old 02-02-13, 08:48 AM
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Tape off the black wire. Your new stat will start your furnace when set for emergency heat using white.

Did you get an outdoor temperature sensor?
 
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Old 02-02-13, 09:42 AM
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Are you still using the fossil fuel kit that should have been in place with the previous thermostat? The Prestige 2.0 can take place of that (if you have and ODT) which will require rewiring the system but it will work much better and automatically switch to aux heat below the outdoor temperature balance point.
 
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Old 02-02-13, 02:27 PM
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Hi hvactechfw,

I could be wrong, but I don't believe there was a fossil fuel kit (the previous owner switched the heat over manually using the Emergency Heat toggle on the previous thermostat).

Yes, I did get the ODT as well as the RedLink setup. I just flipped through the manual again and didn't realize that you could lockout the pump at a certain temp. Do you know which terminal I would need to connect the gas backup to for this to work? Would I just wire the black and white together?

Houston204,

From what I can tell, the black wire is the only way to energize the gas backup (this currently works with it on the L/A terminal when the Thermostat is set to run on Emergency Heat).

Thanks for the responses!
 
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Old 02-02-13, 03:35 PM
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You need to do some more research on your system. If it did not have a fossil fuel kit then it could have done harm to the HP if it ran the furnace at the same time. On a standard HP thermostat if the HP can't keep up it will pull on aux heat this is why a fossil fuel kit with an ODT is necessary for a dual fuel system. Have you checked in the HP for and ODT? How is the HP currently wired? Exactly what redlink setup are you talking about? Do you have the IAQ version of the prestige? Is the white wire not already on aux terminal? You really need to post color/terminal combinations at the thermostat, furnace, and HP. Also, make and model numbers are helpful.
 
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Old 02-02-13, 05:30 PM
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Hi Kevin,

First off, thank you for the responses thus far. Here's what I have for the Thermostat -
Model: Honeywell Prestige THX9321 IAQ w RF EIM and Outdoor Temp Sensor
RedLink: THM600R RedLINK Internet Gateway w/ Wireless Remote Control

White wire is already on the Aux/E terminal. The Black is on L/A.

Wiring:



Heat Pump:
American Standard Heritage 12
Model #: 6H2042A100A2

It's snowing now, so I couldn't get a pic of the wiring. I did not see an ODT, unless it was hidden under something in the unit.

Label:



Furnace:
American Standard Freedom 90
Model #: AUX080C942A

Here's the wiring:
Y2 ----- Yellow
X2 ----- Black
Y1 ----- Yellow
G1 ----- Green
W1 ----- White and Red
X3 ----- Brown
Y3 ----- Yellow
W3 ----- Green
G3 ----- Green
B ----- Blue, Blue, Pinkish White, Blue

 
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Old 02-02-13, 07:38 PM
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ok, the first picture is of a prestige 2.0 sub base. With a standard prestige you do not have and do not use an EIM unit. The last picture is of a fossil fuel kit (TAYPLUS103A?). You need to do some major rewiring to use this thermostat properly (without the fossil fuel kit). Trust me it would be worth the time and effort.


 

Last edited by hvactechfw; 02-02-13 at 08:22 PM.
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Old 02-04-13, 05:09 PM
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Hi Kevin,

Thank you again for the response. I appreciate you taking the time to draw everything out!
I ended up calling a local HVAC company to take a look at it as I realized that with my system and lack of comfort with the current wiring, I'd like a professional to come take a look at it in-person, just in case I left out key details.

I had most everything setup correctly, however, I didn't hook up the thermostat to the humidifier and the fossil fuel kit was locking out the thermostat's control (and vice versa) so the heat pump wasn't turning on anymore. The technician also suggested that we re-wire the whole thing -- he did so and now everything is working great. Basically, he completely bypassed the FFK and the thermostat now controls everything with the outdoor temp sensor. The gas is now set as the Aux/Em Heat and seems to be workign correctly as it's below 30 right now and the gas is running as it should.

All in all, I really appreciate your responses; I just wasn't comfortable making significant wiring changes as I was afraid of missing a key detail or having left out something that could've been relevant. While it definitely would've been cheaper for me to do it myself, $160 is a small price to pay for peace of mind (and to take advantage of all of the features of my thermostat!).

Thank you again and take care,

Chris
 
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Old 02-04-13, 07:32 PM
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30˚ is awful "warm" of a temp to shut down the heat pump. I've set them at 20˚, and lock out the Aux heat at 35˚.
 
 

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